Combined ramjet-pulsejet unit with variable area propelling nozzle



6, 1957 I M. KADOSCH ETAL 2,801,515

7 comsmao RAMJET-PULSEJET UNIT WITH VARIABLE AREA FROPELLING NOZZLE Filed June 1, 1953 2 Sheets-Sheet l Aug. 6, 1957 nosc ETAL 2,801,515

COMBINED RAMJET-PULSEJET UNIT WITH VARIABLE AREA PRQPELLING, NOZZLE Filed June 1, 1953 2 Sheets-Sheet 2 z/v VENTO R 5 United States Patent COMBINED RAMJET-PULSEJET UNIT WITH VARIABLE AREA PROPELLING NOZZLE Application June 1, 1953, Serial No. 358,667 3 Claims priority, application France June 5, 1952 r Claims. (c1. Git-35.6)

In U. S. patent application Ser. No. 263,666, filed December 27, 1951, a method is described by which the flow of a gaseous fluid along a wall may be controlled, which method consists in directing on to the flow to be controlled, an auxiliary flow of a gas at a suitable pressure, the initial velocity of which has a component at right angles to that flow. The output of the auxiliary gas may be only a small fraction, which furthermore is variable, of the output of the flow to be controlled.

The object of the present invention is to indicate a new application and also to suggest new ways of putting this method into etfect together with devices intended to put it into practice.

This new application concerns the control of the crosssectional area of the propelling nozzle formed at the end of a cowling containing one or more pulse-jet units. The auxiliary restriction-jet which discharges laterally into the propulsive jet at the outlet orifice of this cowling is supplied from the combustion chambers of the pulse-jet units, and in particular by the gases which tend to flow back during each explosion, through aerodynamicallyoperating inlet valves of these units or through the air intake in the case of valveless pulse jet units.

The description which follows below with reference to the attached drawings (which are given by way of example only and not in any sense by way of limitation) will make it quite clear how the invention is to becarried into efiect, the special features which are referred to, either in the text or in the drawings, forming, naturally, a part of the said invention.

Figs. 1 and 2 are diagrammatic views in axial section of a composite jet engine having pulse-jet units with a ram-jet cowling.

Figs. 3 and 4 are partial views of two alternative forms of the invention.

In Fig. 1, there have been shown a plurality of pulsejet units 24 arranged in the interior of a cowling 25 of a ram-jet unit having a ramming intake 26 and a propelling nozzle 27. The pulse-jet units 24 are provided with tubular air-inlet passages 16 which open into that portion of the cowling 25 at which the air entering by the intake 26 has been sufliciently slowed down by virtue of the diverging shape of this intake. The tubular passages 16 constitute aerodynamically-operating valves, i. e. they are so designed as to otter a low resistance to the flow of air towards the combustion chambers of the pulse-jet units and a very much higher resistance to the flow in the opposite direction of the gases generated in these chambers by the explosions. Arrangements of this kind have been described previously, for example in Patent No. 2,670,011, issued February 23, 1954, and in patent application Serial No. 229,945, filed June 5, 1951.

The combustion chambers of the pulse-jet units are arranged in the central portion of the cowling 25 in such a way that the heat transmitted through the wall of these chambers is used to heat the air which passes around the said chambers inside the cowling 25 and thus performs an athodyd or ram-jet cycle.

The exhaust nozzles 28 of the pulse-jet units discharge towardsthe rear of the cowling 25. The jet which issues from the propelling nozzle 27 of the cowling 25 is thus made up of a mixture of the combustion gases of the pulse-jet units and of the air which has passed through the cowling 25 around thesepulse jet units in heat-exchange relation therewith. i V

As the aerodynamically-operating valves 16 of the pulse-jetunits'always allow a part of the gases of cornbustion to escape, these gases may be utilized as an auxiliary fluid to vary the effective cross-section of the outlet orifice of the nozzle 27 of the cowling 25.

In the embodiment of Fig. l, tubular members 29 are arranged opposite to and generally coaxially with the aerodynamically-operating valves, their openings being located at a certain distance from the latter. These tubular members 29 receive the gases which escape back through the aerodynamically-operating valves and direct them into an annular chamber 30 formed in the walls of the cowling 25. From this chamber, the gases escape towards the rear through an annular blowing slot 31 provided around the exhaust orifice of the nozzle 27 and suitably arranged and inclined so that the thin annular jet of gas formed in this way has a component of speed at right angles to the axis of the cowling 25. This annular jet acts with its total pressure on the gas flowing through the exhaust orifice of the nozzle 27, whilst this gas in motion only resists the action of the annular jet by virtue of its static pressure, which is relatively low, since this gas has been expanded in its passage through the propelling nozzle to form the high speed propulsive jet. The auxiliary jet expelled from the slot 31 thus varies the eflective outlet area of the propelling nozzle 27, and as the energy of this auxiliary jet varies with the running of the pulse-jet unit, the control thus obtained is automatic.

In the alternative embodiment shown in Fig. 2, the tubular members 29 which collect the gases escaping back through the aerodynamically-operating valves 16 direct them into a central chamber 32 which is extended towards the rear of the ram-jet and is provided with an annular blowing slot 33 a little way forward with respect to the exhaust orifice of the nozzle 27. The gases issuing from this slot have a component of speed at right angles to the main flow, the cross-sectionof passage of which is thereby reduced.

If the auxiliary blowing fluid has a considerable output, and if it becomes necessary to vary the cross-sectional area of its passage, this can be carried out up to a certain point by using the action of the main jet and suitably arranging the orifice or orifices through which the blowing fluid is discharged.

Fig. 3 shows an arrangement of this kind which is applicable to the embodiment of Fig. l. The external wall of the blowing slot 31 is extended by a portion 34, which may be flat or conical or any other shape which is suitable, so that the blowing fluid discharged through the slot 31 against the wall 34 which projects into the main flow, has its area reduced by the main flow, whilst the cross-sectional area of passage of the latter continues to be controlled by the action of the blowing fluid.

Fig. 4 shows an arrangement of the same kind applied to the embodiment of Fig. 2. In this case, the downstream wall 34 of the slot 33 forming a centrifugal auxiliary jet, projects into the main flow through the propelling nozzle, so that the latter flow will exert a restriction action on the auxiliary jet which, in its turn, causes a similar action on the main flow.

What we claim is:

1. In a jet propulsion engine of the ram-jet type having a cowling ending with a propelling nozzle and at least one pulse-jet unit inside said cowling, adapted to generate pulses of combustion gases, nozzle means opening into said propelling nozzle near the outlet thereof, at a substantial angle with the axis of said propelling nozzle, for forming, when supplied with gas, an auxiliary screen-like jet issuing into said propelling nozzle in a generally crosswise direction, means for collecting part of said combustion gases, and duct means extending between said collecting means and said nozzle means.

2.-- An engine as claimed in claim 1, wherein the pulsejet unit'comprises a tubular air intake of the valvelcss type, and the collecting means comprises a tubular memher having an orifice spaced from and facing said intake.

3. An engine as claimed in claim 2, comprising a plurality of pulse-jet units associated with individual tubular members for collecting gases issuing from the intakes of said units, said tubular members being connected with the nozzle means through a common duct means.

4. An engine as claimed in claim 1, wherein the duct means is of generally converging shape, whereby velocity is imparted to the collected gases before they issue from the nozzle means.

5. An engine as claimed in claim 1, wherein the nozzle means is bounded by two walls generally staged along the flow direction through the propelling nozzle, an upstream Wall and a downstream wall, said downstream wall projecting into said propelling nozzle relatively to said upstream wall.

Ref i'ences Cited in the file of this patent UNITED STATES PATENTS 1,801,007 Jezler Apr. 14, 1931 2,543,758 Bodine Mar. 6, 1951 2,628,471 Dunbar Feb. 17, 1953 2,639,580 Stuart Mar. 26, 1953 

